Safety means for hydraulic presses and the like



26, 1967 H. R. BUCY 3,359,598

SAFETY MEANS FOR HYDRAULIC PRESSES AND THE LIKE Filed April 13, 1965 2Sheets-Sheet l JNVEMra/e firmaueg.

H. R. BUCY Dec. 26, 1967 SAFETY MEANS FOR HYDRAULIC PRESSES AND THE LIKEFiled April 13, 1965 2 Sheets-Sheet 2 .r fiy ,B. 0534 I INVENTOR.

flrmemy United States Patent 3,359,598 SAFETY MEANS FOR HYDRAULICPRESSES AND THE LIKE Harry R. Bucy, 550 N. Brighton St., Burbank, Calif.91506 Filed Apr. 13, 1965, Ser. No. 447,809 16 Claims. (Cl. 1816)ABSTRACT OF THE DISCLOSURE A safety means for press type machines havingstationary and moving die or mold carrying platens; said safety meanscomprising devices for interposing a bar between the platen, when theyare separated to effect opening of the mold, and other devices foreffecting the removal of the bar by means which, after first to removingthe bar, initiates the operation of the machine after the bar has beenremoved or, in other words, in which the bar is removed as a priorincident only to the intentional actuation of the machine.

This invention relates to fluid pressure operated press mechanisms suchas pressure die casting machines and injection molding machines forplastics as well as trimming presses and the like operated by fluidpressure cylinder and piston means and relates more particularly to asafety means serving to prevent unintended closing of the mold or diesor other instrumentalities.

By way of example, in the operation of certain machines of the type forwhich the invention is intended, a mold comprising a fixed or cover diehalf and a movable or ejector die half are held in juxtaposition underhigh clamping pressure while molten material is injected into the cavityformed by the two halves of the mold. When the mold is opened by theretraction of the ejector half, the operator must reach between theseparated halves to remove the finished part, clean, and if necessary,lubricate the cavity surfaces. If any machine malfunction should occurcausing the mold to close while he is thus occupied, the operator islikely to have his hand or arm caught between the mold halves, resultingin the loss of the member thus caught and at times, the injury thuscaused has been known to be fatal. A similar hazard exists in all fluidpressure operated press mechanisms. A desire has often been expressed bymembers of Industrial Safety Commissions and like Governmental bodiesfor some sort of device which would prevent the unintended closure ofmolds of this character and which is not dependent on the machineoperator. In other words, the desire is for a device which automaticallywill serve to prevent unintended closure of the halves of a mold by theexpedient of automatically interposing a blocking member capable ofpreventing advance of the ejector half toward the cover half of themold.

Other presently co-pending applications of the present applicant dealwith situations deriving from breakage or other malfunction with thehydraulic cylinder which closes and opens the mold but those inventionsdo not cover the situation involving machines not equipped with thatsafety piston and piston rod nor the hazards deriving from such hazardsas a leaking control valve or a broken operating toggle mechanism eitherof which might thus cause the ejector half of the mold to be movedunintentionally to closed position.

In the following specification reference will be limited to the use ofthe invention on a die casting machine, but from the teaching thus madeavailable, the adaptation of the principles of the invention to otherfluid pressure operated press mechanisms can readily be made by thoseskilled in the art, wherefore it is deemed unnecessary to go intodetails of every possible use of the invention. Ac-

cordingly,.the term mold as'employed in the specification and claimswill be understood to be representation of all dies, molds and the likeemployed in press mechanisms to which the invention is applicable. Also,the term prior incident. will be understood to mean such an associationof control devices that the machine cannot be caused to initiate a cycleof operation until the safety means has been intentionally moved out ofthe path of the moving component of the mold and in which suchintentional movement of the safety means is the means which initiatesthe working cycle of the machine.

With these considerations in mind, it is an object of the presentinvention to provide a safety means for fluid pressure piston operatedmachines such as die casting machines, injection plastic moldingmachines or press mechanisms directly actuated by low pressure pistonand cylinder means, which safety means normally interposes a rigidmember between the relatively moving members of the machine when themold is opened and which is effective thereby to prevent unintendedmovement of the ejector half of the mold toward the cover half to anextent suflicient to injure an operator in which safety means is sointerlocked with the control means for the machine as to render themachine incapable of operation while the rigid member is so interposed.

Another object of the invention is to provide a safety device of theabove character which is rendered inoperative to prevent closing of themold only as an incident to intentional closing of the mold.

Still another object of the invention is to provide a device of theabove character which is simple in design and capable of installation onany machine of the type for which it is intended regardless of whetherthe existing control for the machine which is subject to manipulation bythe operator is pneumatic, hydraulic or electrical.

With the foregoing objects in view, together with such additionalobjects and advantages as may subsequently appear, the invention residesin the parts, and in the construction, combination and arrangement ofparts described, by Way of example, in the following specification ofcertain presently preferred embodiments of the invention, referencebeing had to the accompanying drawings which form a part of saidspecification and in which drawings:

FIGS. 1a, 1b and 1c are side elevational views of a typical pressure diecasting machine and showing diagrammatically the invention appliedthereto With different modes of machine control and associated operatingmeans for the closure preventing component and in which:

FIG. 1a shows a pneumatic pressure controlled, hydraulic pressureactuated system which is based on a manually operable air valve, themachine being shown in open position preliminary to being operated toeffect closing of the mold,

FIG. 1b shows a control system which may be used with either hydraulicor pneumatic pressure and which includes a manually operated valvecontrolling the action of a pilot valve which controls the operatingpiston of the machine; the machine being shown with the mold closedpreliminary to operating the control to open the mold, and

FIG. 1c shows an electrically controlled pneumatic or hydraulicoperating system which is based on a manually operated electric switch,the controls being shown as they exist at the conclusion of a moldopening movement of the cylinder of the machine,

FIG. 2 is a greatly enlarged side elevational view of the mold closingpreventing component of the device in the position occupied uponinitiation of the mold opening portion of the operating cycle, otherpositions thereof being indicated in broken lines,

FIG. 2a is a fragmentary view of a portion of the device shown in FIG. 2but showing the addition thereto of a micro-switch which is employed inthe embodiments of the invention shown in FIGS. lb and 1c,

FIG. 3 is a sectional view taken on the staggered line 3--3 of FIG. 2,

FIG. 4 is a fragmentary sectional view taken on the line 44 of FIG. 2,and

FIG. is a further enlarged, fragmentary side elevational view, partly insection showing an alternative mode of use of the safety bar operatingcylinder which may be employed in any of the embodiments of theinvention.

Referring first to FIGS. 1a, 1b and 1c there is shown a die castingmachine comprising a base A, a platen B for the cover half C of the moldrising from the base, a head member D rising from the base A andcarrying a hydraulic cylinder E operably in which a piston E isreciprocable; said piston being connected by a piston rod F through aninterposed toggle link mechanism F to the platen G and said platen beingslidably mounted on the rods H extending between the platen B and headmember D and said platen carrying the ejector half I of the mold.

The mold closure preventing component of the i1lustrated embodiments ofthe present invention is disclosed in detail in FIGS. 2 through 5 and,since it is substantially identical in all the embodiments of theinvention, it will be described first. This component comprises avertical bracket member I mounted closely above one of the tie rods Has, for example, on the platen B. Adjacent to the platen B, the bracketis provided with a slot extending therethrough parallel to the directionof movement of the ejector half of the mold and a horizontal pivot pin 2extending across said slot serves as a pivotal mounting for one end of asupporting arm 3 for the stop bar to be presently described. At itsupper end, the bracket member 1 carries a short horizontal arm 4extending toward the ejector half of the mold and a pivot pin 5extending through said distal end ofsaid arm parallel to the pivot pin2, pivotally secures the forked end of the head end 6 of a pneumaticcylinder 7 to said arm 4. The opposite end of the cylinder 7 constitutesa combined head and guide means 8 for a piston rod 9 which, within thecylinder 7, is connected to a piston 10 and the other end of said pistonrod carries a head element 11 which is pivotally secured to ear means 12on the distal end of the arm 3 by a pin 12'. The cylinder head member '8is provided with a port 13 which is connected by a passage 14 to theinterior of the cylinder at the side of the piston -10 which is adjacentto said head member 8. A nipple 15 alfords connection between the port13 and one end of a hose 16, the other end of which is connected tocontrol means to be presently described.

The arm Scarries a depending bracket element 17 which, in turn, carriesa sleeve member 18 extending parallel to the arm 3. Removably' disposedin this sleeve is the stop bar element 19 secured the-rein by a setscrew 20. In FIGS. 1a and 10, this bar is shown disposed between theopposed faces. of the support B and platen G the bar being slightlyshorter than the distance between said opposedfacs for a reason to bepresently referred to. It will be obvious that when the stop bar is inthis position, any malfunction in the hydraulic cylinder and pistoncannot cause the ejector half to be brought into contact with the coverhalf.

Referring now to FIG. 1a, the control means for the hydraulic cylinder Eand the piston E and the piston rod F comprises the reversible valve Jand this valve, in turn, is operated by a double acting pneumaticcylinder 21 containing a piston carried by a piston rod 22, the pistonrod being connected by a pivot pin 23 to the operating arm I of thevalve, I here shown as a rotary disk type valve, but any suitablereversing valve, whether rotary, spool, poppet or any other form, can ofcourse be employed. The actuating means, for the piston and piston rod22 comprises the manually operable, reversing pneumatic valve 24 whichis connected by lines 25 and 26 to the opposite ends of the cylinder 21.The inlet port of the valve 24 is connected to a source of compressedair by a line 27 and a line 28 serves as the exhaust from said valve.Again, while a disk type valve is shown, any suitable form of reversingvalve may be employed. The said other end of the hose 16 is connected bya T-fitting 29 to the line 25.

In describing the operation of the device shown in this figure, it willbe assumed that the valve 24 has been moved to the position shown inFIG. 1a and that the parts of the machine affected thereby havecompleted their respective movements in consequence thereof. Thuscompressed air has been conducted through line 26 to cylinder 21 movingpiston 22 to the left with consequent counterclockwise movement of thevalve member of valve J and resultant application of hydraulic fluid incylinder E to move the piston thereof to the right, opening the mold asshown. Movement of the valve 24 in the opposite direction connects theline 25 to the air pressure source represented by line 27 moving piston22 to the right and causing valve J to be moved to connect the outer orright hand end of cylinder E to hydraulic pressure with resultantmovement of piston F thereof to the left and closing of the mold. Theimposition of pressure in line 25 has simultaneously imposed pressurethrough hose 16 to the piston rod end of cylinder 7 and has caused thepiston 10 and piston rod 9 to lift the arm 3 and the stop bar 19 carriedthereby upwardly out of the path of the platen G as it is caused to beadvanced by the piston E and its piston rod, said position beingrepresented by the upper broken line position in FIG. 2. Movement of thevalve 24 back to the position shown in FIG. 1a disconnects line 25 fromthe pressure source and opens it to atmosphere allowing the bar to dropto the full line position of FIG. 2 until the retreating platen allowsit to drop between the platens in the lower dotted line position to theextent permitted by engagement of the piston 10 with the cylinder head 8thus preventing closing of the mold as shown in FIG. 2.

It will be understod that while this operation of the device has beendescribed in a sequential order, in actual usage the entire movement ofthe stop bar to its upward position and the closing of the mold takesplace very quickly, the entire time for the closure of the mold notinfrequently being of the order of less than two seconds. It will benoted that the pressure Will be simultaneously applied to the pistons 10and 22, but since the load imposed on the piston 10 incident to liftingthe bar is less than the load imposed on the piston 22 by the frictionalresistance of the valve J, the piston 10 will have lifted the bar beforethe valve 1 will have been operated to cause the mold closing movementof the machine. However, even if the resistances were of equalmagnitude, the fact that the piston 22- is required to partake of sometravel movement before the valve J is opened, would result in theremoval of the bar before the initiation of the mold closing movement.

The head member or end 6 of the cylinder 7 is provided with a port 30which is normally closed by a plug screw 31. When the, device isactuated to lift the arm 3 and the stop bar 19, the air trapped betweenthe head 6 and the piston 10 is compressed and acts as a spring whichresists the lifting of the arm 3 and stop bar incident to retraction ofthe piston and piston rod so that when the valve 24 is moved to aposition to retract the piston of cylinder 21 through air pressureapplied through line 26, the side of the cylinder connected by the hose16 to line 25 will be connected to the exhaust, whereupon, thecompressed air in the head end of cylinder 7 will assist in moving thearm downwardly until the stop bar 19 rests on top of the retreatingplaten as shown in full lines in FIG. 2. Obviously, before completeretraction of the platen, the stop bar will drop into the position shownin FIGS. 1a and 1c and the lower broken line position shown in FIG. 2,further movement being terminated by engagement of the piston with thehead member 8, finer degrees of adjustment being achieved by thethreaded engagement of the piston rod 9 with head element 11.

Alternatively, as shown in FIG. 5, the plug 31 may be left out and theweight of the stop bar being permitted to cause it to drop first to theposition of repose shown in FIG. 2 and thence to the safety positionabove referred to when the platen has been sufliciently retracted.

The reason for mounting the stop bar 19 in the sleeve 20 is to make itpossible to quickly interchange the stop bars for others of differentlengths to accommodate different mold heights and resultant differentspacing of the platens when the molds are open so that when one end ofthe stop bar is dropped between the platens, the ends of the stop barwill be disposed with the desired minimum clearance therebetween.

-FIG. 1b shows the application of the invention to a die casting machinehaving a manually controlled fluid pressure responsive cylinder andpiston means E for closing and opening the mold, such fluid pressurebeing either hydraulic or pneumatic. In this embodiment, the presentinvention is so incorporated in the line which supplies fluid pressureto effect mold closing movement that introduction of operating pressureinto that line must first effect the actuation of the safety bar liftingmeans before the operating pressure is imposed on the piston of thecylinder E to effect closing of the mold. In the system shown in thisfigure, a manually operated reversing valve 32 (here schematically shownas a disk type valve) has an inlet port connected to a supply ofhydraulic fluid under pressure by a line 33 and an exhaust portconnected to a return line 34 leading to a reservoir (not shown). A line35 connects one port of the reversing valve to the outer end of thecylinder E to supply fluid to eflect the working or mold closing strokeof the piston, said line also being connected to an air line controllingvalve 36 and being interrupted adjacent the connection to the cylinder Eby a solenoid controlled check valve 37 which is a standard article ofcommerce, the construction of said valve being such as will allow fluidto pass therethrough freely from the cylinder E to the valve 32 butwhich will allow fluid to pass therethrough from the valve 32 into thecylinder E only when the solenoid component thereof is energized bymeans presently to be described. The opposite end of this cylinder E isconnected by line 38 with the appropriate port of the reversing valve32.

The valve 36 is a standard article of commerce but will be described inthe manner in which it is employed in the present invention. Thehydraulic port 39 thereof which is connected to the hydraulic cylindersupply line 35 communicates with the chamber 40 within the valve bodyand one side of said chamber is formed by a reciprocable piston 41. Thevalve body is provided with a first air port connected to a source ofsupply of compressed air by line 42, a second port connected to the hose16 and thus to the cylinder 7 by a line 43 and a third port connected toan exhaust line 44. Within the body is a reciprocable valve member 45.carrying the piston 41 and which is biased by a spring 46 to opposehydraulic pressure imposed on the piston. When no pressure exists in thechamber 40, this valve member is moved to maintain the lines 43 and 44in communication with each other. The imposition of line hydraulicpressure in the chamber 40 causes the piston 41 to move the valve meansagainst the bias of the spring 46 to disconnect comunication between thelines 43 and 44 and to interconnect the lines 42 and 43- thus subjectingthe cylinder 7 to air line pressure.

The solenoid of valve 37 is connected with a suitable source of energyby leads 47 and 48, the lead 48 extend ing to one side of a normallyopen micro-switch 50 mounted on the vertical bracket 1 closely adjacentto the pivot pin 2 and having a feeler or operating plunger portion 51positioned for contact by the initial upward movement of the arm 3 asbest shown in FIG. 2a and the other side of terminal of said switch isconnected by lead 49 to the source of energy to complete the circuit.

When the valve 32 is moved to the position shown in FIG. 1b, hydraulicpressure is introduced into the line 35 but since the valve 37 isnormally closed, this fluid is prevented from reaching the outer end ofthe cylinder E, however, the pressure actuates the valve 36 to introduceair pressure to the safety bar operating cylinder with resultant liftingof the safety bar out of the path of the platen G. This closes theswitch 50 energizing the solenoid valve 37 and allowing hydraulicpressure then to enter the cylinder and move the piston to the left withresulting closing of the mold as shown. Reversal of the valve 32 imposesfluid pressure through the line 38 moving the piston to the right andwith consequent expulsion of fluid through the free flow portion of thevalve 37 to the valve 32 and thence to the reservoir of the hydraulicsystem. The lesser pressure in the line 35 allows the spring 46 to movethe valve member 45 to a point connecting lines 43 and 44 and thusestablishing communication of the cylinder 7 with the exhaust port andatmosphere allowing the trapped compressed air therein, or if the port30 is left open, the weight of the stop bar and arm 3 to effect thedropping of the stop bar against the retreating platen and eventualdropping into blocking position as soon as the platen is retractedbeyond the end of the stop bar as shown in FIGS. 2, la and 10. As in thefirst described embodiment, these sequential steps take place so quicklyas to be almost simultaneously.

While this embodiment of the invention comprises a hydraulicallyoperated machine in which the hydraulic system controls the applicationof the pneumatic pressure to the means which lifts the stop or safetybar with resultant opening of a valve to allow the hydraulic pressure toclose the mold, it will be obvious that with suitable modification ofthe valve 36, pneumatic operating pressure might be employed in place ofthe hydraulic pressure means.

FIG. 10 shows the principles of the invention applied to a controlsystem in which the manually operated means comprises an electric switchto be later described, a first solenoid operated valve 522 forcontrolling the supply of operating fluid to the cylinder E, and asecond solenoid operated valve 53 for controlling the supply ofcompressed air to the stop bar operating cylinder 7. This embodiment ofthe invention eliminates the solenoid operated check valve 37 employedin the embodiment shown in FIG. lb. The valves 52 and 53 are standardarticles of commerce and are hence shown only schematically.

The valve 52 is a slide or spool valve having an inlet port connected toa pressure supply line 54, an outlet port connected to a return line 55,a first cylinder port connected by a line 56 to the outer end of thecylinder E and a second cylinder port connected by a line 57 extendingto the opposite end of the cylinder E. The spool component of the valveis moved axially in the valve body 58 by solenoid coils 59 and 60carried by the opposite ends of the valve body.

The valve 53 may be assumed to be substantially the same as the valve 36except for the substitution of the solenoid 61 for the piston 41, foroperating the valve member in opposition to the biasing spring.

In addition to being connected to the solenoids heretofore described,this embodiment of the invention additionally is connected to themanually operated switch 62 which, like the solenoid valve 52,'isstandard equipment on the press mechanism, the pole 62 thereof beingconnected for double throw operation between terminal 63 connected tosolenoid 59 by a lead 65 and terminal 64 connected by a lead 66 to oneside of the micro-switch 50, the other side of said micro-switch beingconnected by a lead 67 to one side of the solenoid 60 of the valve '52,it being noted that when the switch pole is moved to connect the powerlead 63' to the terminal 63, as shown, the solenoid 59 is energized tomove the valve spool to the right with resultant delivery of pressurefluid through line 57 to the left hand or inner end of the cylinder Eand that when the switch pole 62' is moved to connect lead 63 to theterminal 64, the solenoid 60 Will not be energized to move the valvespool to the left With resultant delivery of pressure fluid to the outerend of the cylinder through line 56 until the normally open microswitch50 will have been closed by lifting of the stop bar through pressureapplied to the cylinder 7 by reason of opening of valve 53. Thus themold can not be closed until the stop barhas first been removed.Terminal 64 is also connected by a lead 68 to one side of solenoid 61 invalve 53. The other sides of all three solenoids are suitably connectedto a common power lead 69 to complete the various circuits.

In FIG. 1c, the machine and system are shown at the time that opening ofthe mold has been completed. Solenoid 59 had been energized to causevalve 52 to admit pressure fluid through line 57 to the inner or lefthand end of cylinder E, the mold is completely open and the stop bar hasdropped into safety position. Movement of switch 62 to cause pole 62 tocontact terminal 64 will effect energization of solenoid 61 of valve 53.Energization of solenoid 61 will actuate valve 53 to admit compressedair therethrough to stop bar operating cylinder 7, lifting the stop barand closing micro-switch 50. Closure of this switch completes thecircuit through leads 66 and 67 to solenoid 60 with resultant supply ofpressure fluid to the outer end of cylinder E and consequent closure ofthe mold.

Movement of switch 62 to cause the pole 62' thereof to contact terminal63 will simultaneously open the circuit through solenoid 61 allowing thespring in valve 53 to move the valve member thereof to connect theinterior of cylinder 7 with atmosphere allowing the stop bar to firstdrop on the retreating platen and then drop in front of it asthe platenreaches substantially maximum retraction. By reason of the micro-switchbeing interposed in the operating circuit for the valve operatingsolenoid 60, pressure fluid for closing the mold cannot be supplied tothe cylinder until and unless the stop bar has been moved completelyclear of the path of the advancing platen. As in the other embodiment,it will be appreciated that the various movements of the control systemoccur so quickly after operation of the switch 62 as to be almostsimultaneous. As in the case of the embodiment shown in FIG. lb thefluid pressure may, in some cases, be pneumatic rather than hydraulicfor operating either or both piston elements.

Many machines for which the present invention is intended are providedwith semi-automatic controls which, for'example, are like that shown inFIG. 10 with the addition of a timer means so arranged that when theswitch 62 .is manually operated to initiate a closing stroke the machinecloses the mold or performs such other function as may be required andat the completion of a predetermined interval the switch 62 isautomatically moved to the opposite position. Such machines normallyhave a lead extending from a switch terminal to the solenoid whicheffects the working stroke as, in the present instance, the solenoid 60.In adapting the machine to the improved control on safety means of thepresent invention it would be necessary only to interpose themicro-switch 50 in that lead and connect one side of the valve solenoid61 to terminal 63.

The various embodiments of the invention above disclosed relate to a diecasting machine. It will be obvious to those skilled in the art to whichthe invention appertains that the principles of the invention can beequally well applied to injection molding machines for plastics which,like die casting machines, involve the closure of molds by imposed fluidpressure and the introduction of molten material into the mold cavitiesunder high pressure and in which machines the danger of unintendedclosure of the molds While an operator is reaching between the moldhalves has heretofore been deemed to be a normal risk of the operationof such machines. Obviously, also, the principles of the invention canbe equally Well applied to any press mechanism actuated by a fluidpressure responsive piston means. The illustrated embodiments of thepresent invention provide safety means for die casting machines and theplastic injection molding machines employing separable die or molddevices which virtually eliminates that very great risk; said safetymeans being simple in construction and automatically effective tointerpose a stop member capable of preventing unintended closing of amold and thus to eliminate the ever present danger of maiming anoperator by such unintended closure. Further, as shown in the variousembodiments. of the invention, the principles of the invention are notlimited to any one specific form of machine control but can be appliedto any machine regardless of whether the control of such machine bepneumatic, hydraulic or electrical, all of such manual controls beingknown and used on machines of the character for which the invention isintended. Still further, while the illustrated embodiments of theinvention relate to a machine having separable molds, the principles ofthe invention are not limited to molding machines and may be employed aswell on machines employing dies or other tools in which one component ismoved toward and away from another component by fluid pressure means,

While for purposes of illustration, the invention has been illustratedas applied to a die casting machine subject to full manual operation itis recognized that the more modern die casting and injection moldingmachines are semi-automatic in that upon manual actuation of the switchto effect mold closing, timing devices which form a part of the controlsystem effect the sequential machine operations of filling the mold,holding the mold closed for a predetermined time and then opening themold and coming to a stop. Even with such controls it will be evidentthat the safety bar operating means may suitably be connected foroperation by whatever means is employed to control the main fluidpressure means. Usually, plastic injection molding machines are providedwith a manually opened door through which access to the opened mold ishad and which has a switch associated therewith so arranged that whilethe door is opened, the machine is normally incapable of causing themold to be closed. This is no protection against a malfunction of thecontrol system or the power system not involving the switch which isopened by opening that door. With the device of the present inventioninstalled on the machine, even malfunctions not capable of beingprevented by the access door described can be prevented.

This aspect of the invention has been discovered to have anotherimportant safety factor. There have been instances when static or straycurrents in the automatic control devices have caused an unintendedreversal of the operating switch or of means operated thereby.

The protection afforded by the operator by the positioning of the stopor safety bar between the opened dies or mold halves has been treated atlength above. When and if a malfunction of the control means should havethe same effect as the operation of the switch which initiates movementof the movable mold or die component toward the stationary component,the stop bar, being always in the line of vision of the operator when heis reaching between the dies, by its movement away from its safetyposition gives the operator visual warning that the press is about toclose. This gives him time to get his hand or arm out of the way of theadvancing die or mold half and possibly even time to operate a stopswitch to stop the machine. Without such visual warning in advance ofthe actual closing of the die or mold, it is probable that the mold ordie half will be advancing before he is aware of the malfunction and iscaught and maimed.

' This capacity for giving visual warning of malfunction has anotheradvantage. Knowing (a) that the mold or die can not close so long as thesafety bar is between the halves and (b) that even when the bar is thuspositioned the die or mold can not be closed by a malfunction withoutthe bar being first lifted and thus giving him warning, he is spared themental fatigue of always being on the alert for such unexpectedhappenings and can reach between the opened mold or dies with assuranceof being safe in doing so. In actual tests, this factor has been foundto contribute materially to the productiveness of operators.

Having the foregoing considerations in mind as the invention is shown tobe advantageously applicable not only to machines subject to full manualoperation or to the so-called semi-automatic operation in whichthemachine is manually'caused to start each cycle of operation, but also tofull automatic machines which are manually stopped at will after havingexecuted a plurality of operating cycles,v the references to manualcontrol means or means under control of the operator as employed in theclaims will be understood to embrace all three types of machines abovementioned. Moreover, while certain presently preferred embodiments ofthe invention have been disclosed by way of example, wherefore, it isnot to be inferred therefrom that the invention is limited to theprecise details of construction so disclosed, and it will be understoodthat the invention includes as well, all such changes and modificationsin the parts, and in the construction, combination and arrange ment ofparts as shall come within the purview of the appended claims.

I claim:

1. A safety means for preventing unintended closure of a mold in a fluidpressure actuated press mechanism of the type comprising a framestructure and fixed and movable platen means for supporting the halvesof a mold or die associated with said frame structure fluid pressuremeans on the frame structure operative to move the movable platen meanstoward and away from the fixed platen means and control means forstarting and stopping actuation of the fluid pressure means; said safetymeans being mounted on said press mechanism and comprising a bar ofslightly less length than the distance between the opposed surfaces ofsaid movable and fixed platen means when separated to the greatestextent and normally positioned endwise between the separated platenmeans, a supporting bracket on which said bar is mounted for movementbetween said normal position and another position out of the path ofmovement of the movable platen means toward the fixed platen means, andpower means interconnected with the press mechanism control means andoperatively connected to said bar effective automatically to move saidbar to said other position as a prior incident only to intended movementof the movable platen means toward the fixed platen means.

2. A safety means as claimed in claim 1 in which said supporting bracketis mounted out of the path of movement of the movable platen means, inwhich said power means is arranged to remove said bar from said normalposition when energized, and in which said power means is resilientlyoperative to urge said bar toward said normal position as the movableplaten means of the press mechanism is caused to move away from thefixed platen means.

3. A safety means as claimed in claim 1 in which said supporting bracketis mounted out of the path of movement of the movable platen means, inwhich said power means, when energized, is arranged to remove said barfrom said normal position, and in which said power means is disabled andsaid bar is allowed to return to its said normal position by its ownweight as the movable platen means of the press mechanism is caused tomove away from the fixed platen means.

4. A safety means for preventing unintended closure of a mold in ahydraulic press mechanism of the type comprising a frame structurehaving a fixed platen provided with a surface on which one component ofthe mold is mounted, and a hydraulic cylinder and piston connected toand reciprocating a movable platen carrying the other mold componentinto and out of mold closing engagement with the first named moldcomponent and control means operated by the operator of the machine foractuating the cylinder and piston to effect opening and closing of themold as desired; said safety means being mounted on the press mechanismand comprising a bar of slightly less length than the distance betweenthe mold carrying surfaces of the platens when separated to the greatestextent and normally positioned endwise between the platens when soseparated, a supporting bracket on which said bar is mounted formovement between said normal position and another position out of thepath of movement of the movableplaten, and power means interconnectedwith the press mechanism control means and operatively connected tooperate said bar to move said bar only to said other position as a priorincident to mold closing operation of the press mechanism intentionallyinitiated by the press mechanism control means.

5. A safety means as claimed in claim 4 in which said supporting bracketis mounted out of the path of movement of the mold carrying platen ofthe press mechanism, in which said power means is arranged to move saidbar to said other position when energized, and in which said power meansis resiliently operative to urge said bar toward said normal position asthe mold carrying platens of the press mechanism are caused to separate.

6. A safety means as claimed in claim 4 in which said supporting bracketis mounted above the path of movement of the movable platens of thepress mechanism, in which said power means is arranged to lift said barto said other position when energized, and in which said power means isdisabled and said bar is allowed to fall into its said normal positionby its own weight as the platens of the press mechanism are caused toseparate.

7. A safety means as claimed in claim 4 in which movement of the movableplaten is effected by a hydraulic cylinder and piston controlled by flowreversing valve means and fluid conduits extending between saidhydraulic valve means and the opposite ends of said hydraulic cylinder,in which the one of said conduits through which fluid is supplied fromsaid reversing valve to said cylinder to cause mold closing operation ofthe press mechanism by the piston of said hydraulic cylinder is providedwith a normally closed valve to prevent fluid flow therethrough in adirection to effect mold closing movement, and in which means responsiveto movement of said safety means to its said other position isoperatively connected to effect opening of said normally closed valvewith resultant fluid flow to said cylinder and closing of the mold onlyafter said safety means is moved to the said other position.

8. A safety means as claimed in claim 4 additionally including areversible, pneumatic pressure responsive motor means including anactuated element, a manually operated reversing valve operativelyconnected between said motor means and a source of pneumatic pressure, asecond reversing valve operatively connected to opposite ends of saidhydraulic cylinder and piston for effecting mold opening and closingmovements of the movable platen and including a movable valve elementoperatively connected to said actuated element of said motor means, andpneumatic pressure conduit means connected to operate said bar movingpower means when said manually operated valve is moved to cause saidsecond reversing valve to effect movement of the movable platen towardthe fixed platen with resultant movement of said safety means out ofsaid normal position only incident to closing of the mold.

9. A safety means as claimed in claim 4 in which the direction ofmovement of said press mechanism cylinder and piston and consequentmovement of the movable platen toward and away from the fixed platen iscontrolled by manually operated hydraulic valve means, and in which saidpower means for removing said bar from its said normal positioncomprises a pneumatic pressure responsive cylinder and piston connectedto a source of pneumatic pressure through valve means responsive tohydraulic pressure in a conduit downstream of said manually operatedhydraulic valve means through which fluid is supplied to eifect movementof the movable platen toward the fixed platen.

10. A safety means as claimed in claim 4 in which the press mechanismcontrol includes electric switch means and .an electrically actuatedreversing valve operatively interposed between a source of hydraulicpressure and said hydraulic cylinder and piston and controlled byelectrical connections with said switch, in which a normally closedelectrically controlled valve is interposed between a source ofpneumatic pressure and said power means of said safety means, and inwhich electrical connections extend between said switch and said lastnamed valve operative to open said valve for energization of said powermeans and movement of said bar of said safety means out of said normalposition as an incident to operation of said switch to cause movement ofthe movable platen toward the fixed platen of the press mechanism.

11. A safety means as claimed in claim 4 in which said supportingbracket member is disposed above the mold component carrying surface ofone of the press mechanism platens, in whicha bar supporting arm ispivotally connected to said bracket member adjacent to the press framestructure with the free end of said arm extending toward the other ofthe mold component carrying platens and having means carrying said barspaced from said arm, and in which said power means comprises a pressureresponsive cylinder and piston assembly interconnecting said arm andsaid bracket member .at points thereon remote from said, pivotal,connection and operative in response to pressure induced retraction ofsaid assembly to lift said arm and said bar moving said bar from saidnormal position out of the path of movement of the movable platen of thepress mechanism.

12. A safety means; as claimed in claim 4 in which said bar isdetachably carried by an arm. havingv one end thereof pivotallyconnected to said supporting bracket, and in which said power meansreacts between said supporting bracket and a point adjacent the oppositeend of said arm.

13. A safety means as claimed in claim 4 in Which said bar is carried byan arm having one end thereof pivotally mounted on said supportingbracket, and in which said bar is removably mounted on said arm.

14. A safety means as claimed in claim 4 in which said power meanscomprises a piston and cylinder assembly and in which the engagement ofthe piston of said assembly with an end member of said assembly affordsa stop means determining said normal position of said bar.

15. A safety means as claimed in claim 5 in which said bar is connectedto said bracket for pivotal movement into and out of said normalposition, in which said power means com-prises a cylinder and pistonassembly including a piston rod slidable in a sealed end memberconstituting one end of the cylinder, in which the opposite end of saidcylinder is sealed, .and in which said cylinder adjacent to said one endthereof is provided with a connection affording communication with asource of fluid pressure.

16. A safety means as claimed in claim 6 in which said bar is connectedto said bracket for pivotal movement into and out of said normalposition, in which said power means comprises a cylinder and pistonassembly including a piston rod slidable in a sealed end memberconstituting one end of the cylinder, in which the opposite end of saidcylinder is open to atmosphere, and in which said cylinder adjacent tosaid one end thereof is provided with a connection affordingcommunication with a source of fluid pressure.

References Cited UNITED STATES PATENTS 2,584,534 2/ 1952 Barnhardtson.2,946,277 7/1960 Archer -53 2,990,578 7/1961 Adair et al.

WILBUR L. MCBAY, Primary Examiner.

1. A SAFETY MEANS FOR PREVENTING UNINTENDED CLOSURE OF A MOLD IN A FLUIDPRESSURE ACTUATED PRESS MECHANISM OF THE TYPE COMPRISING A FRAMESTRUCTURE AND FIXED AND MOVABLE PLATEN MEANS FOR SUPPORTING THE HALVESOF A MOLD OR DIE ASSOCIATED WITH SAID FRAME STRUCTURE FLUID PRESSUREMEANS ON THE FRAME STRUCTURE OPERATIVE TO MOVE HE MOVABLE PLATEN MEANSTOWARD AND AWAY FROM THE FIXED PLATEN MEANS AND CONTROL MEANS FORSTARTING AND STOPPING ACTUATION OF THE FLUID PRESSURE MEANS; SAID SAFETYMEANS BEING MOUNTED ON SAID PRESS MECHANISM AND COMPRISING A BAR OFSLIGHTLY LESS LENGTH THAN THE DISTANCE BETWEEN THE OPPOSED SURFACES OFSAID MOVABLE AND FIXED PLATEN MEANS WHEN SEPARATED TO THE GREATESTEXTENT AND NORMALLY POSITIONED ENDWISE BETWEEN THE SEPARATED PLATENMEANS, A SUPPORTING BRACKET ON WHICH SAID BAR IS MOUNTED FOR MOVEMENTBETWEEN SAID NORMAL POSITION AND ANOTHER POSITION OUT OF THE PATH OFMOVEMENT OF THE MOVABLE PLATEN MEANS TOWARD THE FIXED PLATEN MEANS, ANDPOWER MEANS INTERCONNECTED WITH THE PRESS MECHANISM CONTROL MEANS ANDOPERATIVELY CONNECTED TO SAID BAR EFFECTIVE AUTOMATICALLY TO MOVE SAIDBAR TO SAID OTHER POSITION AS A PRIOR INCIDENT ONLY TO INTENDED MOVEMENTOF THE MOVABLE PLATEN MEANS TOWARD THE FIXED PLATEN MEANS.